Impact ionization in AlxGa1−xAs for x=0.1–0.4

Abstract

The impact ionization coefficients in AlxGa1−xAs have been experimentally determined for compositions x≤0.4. These data are necessary for accurate device design and modeling. Both α, the electron ionization coefficient, and β, the hole ionization coefficient, decrease with increasing x, and there is no appreciable change in the ratio α/β over the range of compositions and electric fields studied.

Avalanche multiplication in Al/sub x/Ga/sub 1-x/As (x=0 to 0.60)

“…magnitude of and decrease while [4] shows the / ratio decreases such that for Robbins et al [5] measured and from abrupt one-sided homojunctions with to 0.40 and found reasonable agreement with [4] except that for all alloys. In [4], [5] however, local ionization theory was used to deduce and whereby these parameters are assumed to vary with solely the local electric field.…”

“…In [4], [5] however, local ionization theory was used to deduce and whereby these parameters are assumed to vary with solely the local electric field. While this analysis can be justified in devices with thick avalanche regions, such that most carriers are in equilibrium with the field, the avalanche regions of modern transistors can be m [6].…”

Performance of thin separate absorption, charge, and multiplication avalanche photodiodes

“…8. The calculated gain using the ionization coefficients that were fitted for the homojunction APD's gives a reasonable fit to the measured data, and a much better fit than the gains predicted using the reported "bulk" ionization coefficients [25], [26].…”

“…Structures containing multiple-quantum-well (MQW) multiplication regions have been proposed as a way to reduce the excess noise in APD's [22], [23], but Hu et al [24] have shown that comparable reductions in noise can be achieved by using thin multiplication layers. If ionization coefficients for 'bulk' GaAs and Al Ga As from [25] and [26], respectively, are used, the fit to our measured data is poor, especially for the thinnest APD's. The "bulk" ionization rates do not fit the measured excess noise factors and predict increasing excess noise factors with decreasing multiplication width, contrary to the observed trends.…”

Field Plate Devices for RF Power Applications

“…Concerning the physical parameters and the numerical simulations, the device structure in figure 1 has been simulated by means of hydrodynamic simulation by taking into account both gate tunnelling effects from the gate terminal and impact ionization phenomena in the InGaAs, GaAs and AlGaAs region of the device. Particularly, impact ionization coefficient used for simulation are those reported in (Robbins et al, 1988) for GaAs and AlGaAs and (Bhattacharya et al, 1986) for the InGaAs. Finally, during simulation a donor trap located at the SiN/GaAs interface with a 8x10 12 cm-2 density has been taken into account.…”